The objectives of these investigations are the understanding of the manners in which fatty acids (and their derivatives) are biosynthesized and interconverted in general and in specific organs and tissues and the factors (dietary, hormonal, pathological, age) which influence these processes. These studies seek to understand the relationship of cellular structures to these processes and the role of specific fatty acids, particularly polyenoic acids, in the physiological function of particular organs or tissues. Experiments with intact animals, perfused organs and in vitro preparations of homogenates and subcellular fractions will be used with radioactive substrates to elucidate these reactions. Methodology includes use of column, thin-layer and gas chromatography, liquid scintillation beta spectrometry, gas radiochromatography, and chemical degradations. Results of these studies, which are a part of long-term continuing investigations of this laboratory on basic aspects of lipid metabolism, will aid us in the goal of knowing eventually the origin, alterations, and fate of the important fatty acids in each organ and tissue, with an understanding of the enzyme mechanisms responsible for the reactions, the important factors causing alterations, and the conditions necessary to regulate the processes of production, interconversions, and utilization of the fatty acids in a manner compatible with a healthy "normal" life.